Thursday, November 15, 2012

Newswise — CORVALLIS, Ore. – Eight researchers in a new report
have suggested that climate change is causing additional stress to many
western rangelands, and as a result land managers should consider a
significant reduction, or in some places elimination of livestock and
other large animals from public lands.
A growing degradation of
grazing lands could be mitigated if large areas of Bureau of Land
Management and USDA Forest Service lands became free of use by livestock
and “feral ungulates” such as wild horses and burros, and high
populations of deer and elk were reduced, the group of scientists said.
This
would help arrest the decline and speed the recovery of affected
ecosystems, they said, and provide a basis for comparative study of
grazing impacts under a changing climate. The direct economic and social
impacts might also be offset by a higher return on other ecosystem
services and land uses, they said, although the report focused on
ecology, not economics.
Their findings were reported today in Environmental Management, a professional journal published by Springer.
“People
have discussed the impacts of climate change for some time with such
topics as forest health or increased fire,” said Robert Beschta, a
professor emeritus in the College of Forestry at Oregon State
University, and lead author on this study.
“However, the climate
effects on rangelands and other grazing lands have received much less
interest,” he said. “Combined with the impacts of grazing livestock and
other animals, this raises serious concerns about soil erosion, loss of
vegetation, changes in hydrology and disrupted plant and animal
communities. Entire rangeland ecosystems in the American West are
getting lost in the shuffle.”
Livestock use affects a far greater
proportion of BLM and Forest Service lands than do roads, timber harvest
and wildfires combined, the researchers said in their study. But effort
to mitigate the pervasive effects of livestock has been comparatively
minor, they said, even as climatic impacts intensify.
Although the
primary emphasis of this analysis is on ecological considerations, the
scientists acknowledged that the changes being discussed would cause
some negative social, economic and community disruption.
“If
livestock grazing on public lands were discontinued or curtailed
significantly, some operations would see reduced incomes and ranch
values, some rural communities would experience negative economic
impacts, and the social fabric of those communities could be altered,”
the researchers wrote in their report, citing a 2002 study.

Among the observations of this report:
• In the western U.S., climate change is expected to intensify even if greenhouse gas emissions are dramatically reduced.
•
Among the threats facing ecosystems as a result of climate change are
invasive species, elevated wildfire occurrence, and declining snowpack.
•
Federal land managers have begun to adapt to climate-related impacts,
but not the combined effects of climate and hooved mammals, or
ungulates. • Climate impacts are compounded from heavy use by
livestock and other grazing ungulates, which cause soil erosion,
compaction, and dust generation; stream degradation; higher water
temperatures and pollution; loss of habitat for fish, birds and
amphibians; and desertification.
• Encroachment of woody shrubs at
the expense of native grasses and other plants can occur in grazed
areas, affecting pollinators, birds, small mammals and other native
wildlife.
• Livestock grazing and trampling degrades soil
fertility, stability and hydrology, and makes it vulnerable to wind
erosion. This in turn adds sediments, nutrients and pathogens to western
streams.
• Water developments and diversion for livestock can
reduce streamflows and increase water temperatures, degrading habitat
for fish and aquatic invertebrates.
• Grazing and trampling
reduces the capacity of soils to sequester carbon, and through various
processes contributes to greenhouse warming.
• Domestic livestock
now use more than 70 percent of the lands managed by the BLM and Forest
Service, and their grazing may be the major factor negatively affecting
wildlife in 11 western states. In the West, about 175 taxa of freshwater
fish are considered imperiled due to habitat-related causes.
•
Removing or significantly reducing grazing is likely to be far more
effective, in cost and success, than piecemeal approaches to address
some of these concerns in isolation.
The advent of climate change
has significantly added to historic and contemporary problems that
result from cattle and sheep ranching, the report said, which first
prompted federal regulations in the 1890s.
Wild horses and burros
are also a significant problem, this report suggested, and high numbers
of deer and elk occur in portions of the West, partially due to the loss
or decline of large predators such as cougars and wolves. Restoring
those predators might also be part of a comprehensive recovery plan, the
researchers said.
The problems are sufficiently severe, this
group of researchers concluded, that they believe the burden of proof
should be shifted. Those using public lands for livestock production
should have to justify the continuation of ungulate grazing, they said.
Collaborators
on this study included researchers from the University of Wyoming, Geos
Institute, Prescott College, and other agencies.